The present disclosure relates to a control device for controlling a vehicle drive system.
Hybrid vehicles that use both an internal combustion engine and a rotating electric machine as a source to drive wheels are in practical use. As one example of a vehicle drive system used in such hybrid vehicles, a system disclosed in Japanese Patent Application Publication No. 2007-99141 is known. The vehicle drive system of Japanese Patent Application Publication No. 2007-99141 includes an engagement device (a first clutch 6), a rotating electric machine (a motor/generator 5), and a multi-stage automatic transmission (an automatic transmission 3) that are provided in a power transfer path connecting an internal combustion engine (an engine 1) to wheels (right and left rear wheels 2).
The vehicle drive system of Japanese Patent Application Publication No. 2007-99141 is structured to achieve the following modes: an electric travel mode that allows a vehicle to travel on the torque of the rotating electric machine with the engagement device in a disengagement state; and a hybrid travel mode that allows the vehicle to travel on the torques of the internal combustion engine and the rotating electric machine with the engagement device in an engagement state. When a mode switches from the electric travel mode to the hybrid travel mode, a control device for controlling the vehicle drive system of Japanese Patent Application Publication No. 2007-99141 brings the engagement device into a slip engagement state and performs start control of the internal combustion engine by using the torque of the rotating electric machine. At this time, the transfer torque capacity of the engagement device brought into the slip engagement state is set in accordance with the magnitude of a torque required to raise the rotational speed of the internal combustion engine.